A constant, or data literal, is a symbolic expression that represents a specific value
of a specific data type in SQL Server Transact-SQL.
Constants or literals are used commonly as the default values for table columns, variables, and parameters.

Constants or data literals are also used as operands to construct operations and expressions.

Here are some examples of data literals SQL Server Transact-SQL:

-2255 -- A literal represents a negative integer of -2255
1894.1204 -- A literal represents a decimal number of 1894.1204
9.22337e+3 -- A literal represents a floating number of 9223.37
'FYIcenter.com' -- A literal represents a single-byte string
N'FYIcenter.com' -- A literal represents a Unicode string
0x69048AEFDD010E -- A literal represents a binary string
€542023.14 -- A literal represents a currency value